Bicyclic oxazolidines are generally known and used as hardeners, corrosion inhibitors, lubricants, adhesive additives, enamel coatings and curing agents as described in U.S. Pat. Nos. 4,064,055, 4,277,353, 4,277,354, 3,982,993, 3,888,625, 3,802,897, 3,773,730, 3,725,350, 3,738,992, 3,706,950, 5,187,019, 5,684,114, 3,802,897, 3,705,832, 3,695,326, 3,281,311, 3,256,137, 3,281,310 and 3,297,611. Mixtures of bicyclic oxazolidine, used as a preservative in latex paints and emulsions, pigmented dispersions, slurries, adhesives, caulks, sealants and metal working fluids to prevent bacterial decomposition have been described in ISP BIOTREND bulletin 0040-R6, dated March 2002 One such mixture is marked under the trademark NUOSEPT 95. Also, a limited group of monocyclic oxazolidines disclosed in U.S. Pat. Nos. 4,841,064, 4,855,312 and Canadian patents 1,221,096 and 1,252,041 are defined as having biocidal properties.
Additionally, the preparation of the bicyclic compounds is set forth in technical bulletins TB 15 and TDS 40 issued by ANGUS Chemical Company and involves the condensation reaction between equimolar amounts of paraformaldehyde and an aminoalcohol. One of the challenges facing oxazolidine manufacturers and formulators using this product is the presence of free formaldehyde which has been found objectionable from human safety and environmental considerations. The stringent limits of formaldehyde in human exposure and air emissions imposed by foreign and domestic agencies, such as the Occupational Safety and Health Administration and the Environmental Protection Agency, require costly purification in the manufacture and use of formaldehyde derived oxazolidines. Additionally, in the manufacture of biheterocyclic compounds such as oxymethylene oxazolidine, it is desirable to minimize or eliminate the formation of alkoxylated derivatives which significantly reduce its activity and stability.
IPBC has been independently described as a biocide for certain algae in U.S. Pat. No. 6,121,198. However, this carbamate exhibits mostly antifungal efficacy against several other species.
Accordingly, it is an object of this invention to provide a broad spectrum antimicrobial liquid composition which has less than 0.1 wt. % of free formaldehyde.
Another object is to provide a liquid biocidal oxazolidine composition which is non-toxic to humans and safe for incorporation in topical personal care formulations.
Another object of the invention is to provide a commercially feasible and economical process for producing a bicyclic oxazolidine and IPBC mixture containing low levels of free formaldehyde.
Still another object is to prepare a synergistic mixture of biocides which is effective against gram negative and gram positive bacteria as well as fungi.
Still another object is to provide a clear liquid composition containing a mixture of oxazolidine and IPBC which is resistant to precipitation or crystallization and which is substantially colorless.
These and other objects and advantages of the invention will become apparent from the following description and disclosure.